Precondition battery when going to 50Kw charger?

[PagodaY]

I noticed the other day when navigating to a 50Kw charger that the car attempts to pre-condition the battery for faster charging. It's nice that my 2020 MY recognizes the non-tesla charging stop as a charger, but is there really any benefit to having the battery pre-condition when charging at a 50Kw charger?

 

[UncleCreepy]

Depends on the battery temperature and the SoC.
If the SoC is so high that even a perfectly warm battery could only accept 40 kW then there is no point.
If the battery is warm enough to accept more than 50 kW, there is also no point in preconditioning.
It's hard to predict what the charge rate will be without knowing the specifics.

One thing I will say though is that while DC charging, the car will always heat the battery. So if you have an AWD Tesla and the station is showing 50 kW, you'll only charge at a maximum of 43 kW.

 

[PagodaY]

Thanks for the reply.

Every time I've used this particular charger it has shown a rate of 47kW. The other day when the car did it's "pre-conditioning" prior to arrival the rate was also 47kW.

I usually show up at the charger with a SOC in the 30% range and charge to 80% (it's a free charger, so I break for lunch and take as much time as I can!) I don't have a way to monitor the battery temp. (Hint Hint Elon)

Going into the summer months with increased temps, I'm pretty sure the pre-conditioning is wasted electricity. I'll monitor it on today's trip.

thanks again

 

[jcanoe]

Depends on the battery temperature and the SoC.
If the SoC is so high that even a perfectly warm battery could only accept 40 kW then there is no point.
If the battery is warm enough to accept more than 50 kW, there is also no point in preconditioning.
It's hard to predict what the charge rate will be without knowing the specifics.

One thing I will say though is that while DC charging, the car will always heat the battery. So if you have an AWD Tesla and the station is showing 50 kW, you'll only charge at a maximum of 43 kW.

On a recent trip I used a SC that was close to my hotel. There was no point in preconditioning for the SC charging session because the SC was only 1 mile away. The Tesla charging screen displayed a message that the battery was being heated for optimal Supercharging. The charging rate gradually increased until the charging rate started tapering. At some point the battery heating stopped. In this case battery heating resulted in a higher peak charging rate, at least until the battery SOC was close to 70% and then normal tapering down of the charging rate was observed. I used this SC twice. The first time I charged to 80% and the second time 90%.

 

[Park2670]

The batteries need to be warm to charge fast (even at 50kW) and the car will heat it as much as Tesla has deemed necessary to protect the battery.
They recently changed the algorithm to not heat it up as much for slower chargers, and I have noticed it on my car while watching the app ScanMyTesla.

 

[UncleCreepy]

Those are different scenarios than what @PagodaY described. Either way, in terms of battery longevity it doesn't matter whether or not you're preconditioning. The BMS will make sure that the battery is ready to accept a charge. Since OP found a free charger it's more an issue of "how much time do I want to spend here?"

As far as "fast charging" goes, I personally don't consider it fast to charge on a 50 kW charger. Realistically they provide up to 47 kW on a good day and in case of my M3 AWD 7 kW are used for heating, so the battery gets only 40 kW max. With an assumed pack capacity of 75 kWh that's a C-rating of 0.53. For all I know charging below a C-rating of 1 is not considered fast charging. Nevertheless, a minimum temperature threshold needs to be reached in order to charge at a certain power level. Obviously that threshold is higher on a Supercharger than at a 50 kW station.

 

[Rocky_H]

but is there really any benefit to having the battery pre-condition when charging at a 50Kw charger?

It depends. In May or June? No, it won't do anything. But you live in New York. In January? Yes, it might. If your car was parked out overnight, and the temperature was in the teens with a very cold soaked battery, and you drove 5 minutes to the charger, then it might be very limited below 50 kW until it gets a chance to warm up, so it might be helpful.

 

[UncleCreepy]

It depends. In May or June? No, it won't do anything. But you live in New York. In January? Yes, it might. If your car was parked out overnight, and the temperature was in the teens with a very cold soaked battery, and you drove 5 minutes to the charger, then it might be very limited below 50 kW until it gets a chance to warm up, so it might be helpful.

Agreed, although in that scenario it probably would've been better to charge the car the day before when you return instead of letting the battery cool down first. Preconditioning for five minutes won't make much of a difference.

 

[PagodaY]

Thanks for the replys.

The charger in question is about 2 hours away, so the battery would never be in a "cold" state. I've never done the drive/charge in the winter, so I don't know if the charge rate would be impacted, I would assume it would and in that situation, I'd allow the car to pre-condition the battery.

Last week I charged the car at this location. I deliberately did not put the charger location into the nav, so the car did not pre-condition. Temps were in the low 70s, car had been driving for about 2 hours and there was no "Cold battery" indicator. (why can't it display the temp instead of the "idiot light"???). SOC at start of charge was 35%.

Charge rate was the same 47kW as it had been in the past. My app did not show the battery heating icon at first. Towards the end of the session the battery heat icon came on. The charge rate was still 47kW. I left with SOC of 80%. Took about 40 minutes.

So I'm still not sure if it's worth the juice to pre-condition, but it's probably a wash seeing as how the car still used some to condition the battery. Doing it ahead of time might same a few minutes though.

 

[jcanoe]

Thanks for the replys.

The charger in question is about 2 hours away, so the battery would never be in a "cold" state. I've never done the drive/charge in the winter, so I don't know if the charge rate would be impacted, I would assume it would and in that situation, I'd allow the car to pre-condition the battery.

Last week I charged the car at this location. I deliberately did not put the charger location into the nav, so the car did not pre-condition. Temps were in the low 70s, car had been driving for about 2 hours and there was no "Cold battery" indicator. (why can't it display the temp instead of the "idiot light"???). SOC at start of charge was 35%.

Charge rate was the same 47kW as it had been in the past. My app did not show the battery heating icon at first. Towards the end of the session the battery heat icon came on. The charge rate was still 47kW. I left with SOC of 80%. Took about 40 minutes.

So I'm still not sure if it's worth the juice to pre-condition, but it's probably a wash seeing as how the car still used some to condition the battery. Doing it ahead of time might same a few minutes though.

The charging level (47kW) may be limited at that location for other reasons. Was this a Tesla Supercharger or a DC Fast Charge station such as Blink or EVgo? There are many older Blink and EVgo charging locations that offer CHAdeMO and CCS1 charging, that are limited to 50kW. If this was a Tesla Urban Supercharger, these are limited to a 72kW charging rate. With a ~70% state of charged battery and no preconditioning for Supercharging I have observed Urban Supercharger rates as low as 36kW (half the rated maximum).

 

[UncleCreepy]

Was this a Tesla Supercharger or a DC Fast Charge station such as Blink or EVgo? There are many older Blink and EVgo charging locations that offer CHAdeMO and CCS1 charging, that are limited to 50kW.

He mentioned in post #1 that this was a 50 kW non-Tesla charger.

 

[PagodaY]

That is correct, it is a non-tesla charger. I don't know who provides the hardware for this location, but it is free (and very convenient) so I don't really pay attention to the screen other than look at the rate of charge and to press end. I'll check next week.